Corrosion inhibiting composition



2,711,374 Patented June 21, 1955 CORRQSION INHIBHTING COh/iPGSITION Jones I. Wasson and Ben W. Geddes, Union, N. J., as-

signors to Esso Research and Engineering Company, a corporation of Delaware 1 No Drawing. Application August 31, 1951, Serial No. 244,727

2 Claims. (Cl. 106-14) The present invention relates to a corrosion inhibiting composition and particularly to an oily composition of lubricating oil consistency which is suitable for performing the dual functions of lubricating and preventing the rusting of fine machinery and of ferrous metal parts in particular. The present composition is also advantageous in having superior resistance to the corrosion of other metals, particularly cadmium.

Numerous rust inhibiting oil compositions have been proposed in the prior art for various purposes. For the lubrication of fine machinery where it is extremely important to prevent rusting and also where cadmium, or cadmium plated metal parts are involved, prior art compositions have not been entirely satisfactory. It is an object of the present invention to prepare a superior rust inhibiting material which can meet rigid specifications regarding protection of both ferrous metals and cadmium against corrosion under severe operating conditions.

As a base material a lubricating oil of the normal lubrication viscosity range is used and this may be either an oil of mineral base, a synthetic oil, or a mixture of mineral and synthetic oils. Various synthetic oils may be used with or without the mineral oil such as polyglycol type oils, alkyl ethers of polyglycols, or the esters of monoand poly-basic acids. The dialkyl esters of dicarboxylic aliphatic acids are particularly suitable because of their especially good viscosity-temperature relationships. Of these a readily available and preferred material is di-2- ethylhexyl sebacate. Related and homologous materials are equally useful although the particular ester referred to is more commonly available than most of the others.

To a suitable base oil, which although preferably a synthetic ester, may be a mixture or an oil of one of the other types previously mentioned, there is preferably added more about 1 to 5% by weight, based on the total composition, of an emulsifying agent. Such emulsifying agent may be a suitable oil soluble petroleum sulfonate or a natural fatty material such as lanolin or degras with or without a partial fatty acid ester of a polyhydric aliphatic alcohol. Materials of the latter type, which are well known surface active agents are exemplified by pentaerythritol mono-oleate, sorbitan mono-oleate, sorbitan mono-stearate, and related partial esters of various available polyhydric alcohols. Thus the mono-oleate or even the di-oleate of glycerol may be used, the monooleate being preferred. Some or all of these materials may be used in various proportions, for example, 0 to 5% by weight of the oil soluble metal petroleum sulfonate, preferably sodium sulfonate although calcium sulfonates and some of the other oil soluble sulfonates are just about as useful, 0 to 5% of the natural fatty material, degras To an oil composition containing one or more of the above ingredients, there is added from 0.01 to about 2% by weight, based on the total composition, of lecithin. The latter, which has previously been used in mineral oils for some purposes, has been found to be a particularly effective corrosion inhibiting additive, especially in synthetic oils of the type referred to above. Preferred proportions of the lecithin are from about 0.1 to 1% by weight, a range around 0.3% to 0.5% being optimum when the oils contain the other additives mentioned above.

It is desirable also to include in the rust inhibiting oil composition a suitable anti-oxidant as an auxiliary additive. While various types of anti-oxidants can be used, the alkyl phenol type products and the salts thereof which are widely used in the oil industry are particularly suitable. A preferred anti-oxidant of this type is 2,6-ditertiarybutyl paracresol. This may be used in the usual proportions employed for anti-oxidants, that is, in the range of about 0.1 up to 2% by Weight based on the total composition. Proportions of about 0.5% are usually deemed the most satisfactory.

To summarize, the corrosion inhibiting composition which is specifically preferred for the present invention comprises a synthetic aliphatic polybasic acid ester lubricating oil which contains small proportions, from about 0.1 to 5% by weight, based on the total composition, of oil soluble petroleum sulfonate and similar proportions of natural animal fatty material and partial ester of polyhydric alcohol such as pentaerythritol mono-oleate or sorbitan mono-oleate. To these are added the very important ingredients lecithin in proportions of 0.01 to about 2% in combination with 0.1 to 1% of antioxidant, preferably of the alkylated phenol type.

The invention will be more fully understood by reference to specific examples:

EXAMPLE 1 A blend which met the requirements of Government specification MIL-O6085 consisted of di-Z-ethylhexyl sebacate with 1% of oil soluble sodium sulfonate, 1% of degras, 1% of pentaerythritol mono-oieate and 0.5 of 2,6-ditertiary butyl paracresol to which was added 0.3% of lecithin. This formula, without the lecithin, met the specification requirements except for corrosion of cadmiurn in the oxidation test. The addition of lecithin prevented cadmium corrosion. The results are shown in the following table which shows a comparison with a similar blend containing no lecithin, and, with a standard commercial rust preventive oil.

Table l 1 INSTRUMENT OILS It will be noted that omission of the lecithin did not seriously affect performance in preventing rust, but very materially increased corrosion to cadmium.

-13 EXAMPLE 2 Another blend composed of di-Z-ethyl'nexyl sebacate was prepared with 1% by Weight of oil soluble sodium following table:

Table III PROPERTIES OF INSTRUMENT OILS [Base oil=di-2-ethylhexyl sebacate+0.5% 2,6-di-tertiary butyl p-cresol] Humidity Cabinet Corrosion and Oxidation Llfe (HMS) Wt. Change of Metals, MgsJOmfl Neut. Additive No. In

1 h d s d d crease P0 is e an e Panels Panels Cd Cu Fe A1 Mg 1. 1% Lecithin i i 2. 2% Lecithin 166 +0.02 0.05 +0.02 +0.02 +0.03 0.67

3. 2% Lceithin+1% Sodium Petroleum Sultonrite 214 +0.03 0 04 +0.03 +0. 04 +0. 04 85 4. 1 Sodium Petroleum Sulionate+1% Degras 24; 120 l. 7 None None None None 0 20 5. 1% Sodium Petroleum Sultonate+1% Degras |-1% Pentaerythritol Mouo-oielalte i i 7 ij ;i 7 48-120 192-244 1. 7 None None None None 0.20 6. 1 Sodium Petroleum ci tonate egras ientaerythritolMono-oleate+0.3% L eithin .1. 48-120 192-244 None 0. 04. 0. 04 None None 0.17 7. 1% Sodium Petroleum Sulfonate+l% Degras-HZ,

Ientacrythritol Mono-oleate+0.75% Lecithin 121 192-244 0. 02 O. 15 None None None 0. a5

Underliuiug indicates failure to meet specifications.

Note that blend 6 with 0.3% lecithin is borderline in humidity cabinet performance, while blend 7 with 0.75% is borderline in neut. No. increase. A blend containing 0.5 to 0.6% would be expected to pass both tests.

petroleum sulfonate, 1% degras, 1% lecithin and 0.5% of 2,6-ditertiarybutyl paracresol. This product complied It will be understood that various of the additives mentioned above, other than lecithin, can be omitted, in some with the requirements of specification MlLO 6085, as 30 cases or their proportions increased or decreased for parshown in the following table. Here again, a similar composition without lecithin was prepared for comparison.

As in Example 1 it will be noted that excessive corrosion of cadmium resulted when the lecithin was omitted. The humidity cabinet test was much inferior without the lecithin.

Petroleum base oils, or blends of petroleum oils with di-Z-ethylhexyl sebacate can be used with the same general results.

ticuiar uses Without departing from the spirit of the invention. Gther materials which do not afiect the rust preventive properties, such as thickeners, viscosity index Table H improvers, metal deactivators, and the like may also be Corrosion and 35 incorporated in the usual proportions as will be apparent Oxidation to those skilled in the art.

Wt. Change of Metals What IS clalmed 1S} Cabinet (Mgs/Gm?) 1. A corrosion inhibiting composition for fine nia- Life (Hm) chinery comprising a major proportion of a dialkyl ester Copper Cadmmm of dibasic aliphatic carboxylic acid as a lubricating oil, about 1% by Weight of oil-soluble petroleum sulfonate, g 3, about 1% of degras, about 1% of pentaerythritol monooleate, about 0.5 to 0.6% of lecithin and about 0.5% of 2,6-ditertiary 'outyl paracresol.

5 2. A corrosion inhibiting composition for fine machinery comprising a major proportion of di-Z-ethylhexyl sebacate, about 1% by weight of oil-soluble sodium petroleum sulfonate, about 1% of degras, about 1% of pentaerythritol monooleate, about 0.5 to 0.6% of lecithin and about 0.5% of 2,6-ditertiary butyl paracresol.

References Cited in the file of this patent UNITED STATES PATENTS 2,212,021 Hendrey Aug. 20, 1940 2,257,601 Hall Sept. 30, 1941 2,265,582 Stevens et al. Dec. 9, 1941 2,339,797 Musher Jan. 25, 1944 2,403,284 Jacobs July 2, 1946 2,539,503 Zisman M Jan. 30, 1951 2,560,202 Zimmer et al. July 10, 1951 2,564,422 Barnum Aug. 14, 1951 2,564,423 Barnum Aug. 14, 1951 2,634,237 Kopf Apr. 7, 1953 OTHER REFERENCES Rees et 211., Use of Lecithin in Gasoline, Proceedings, American Petroleum Institute, 21st Annual Meeting, Section III, 1940, pages 6 to 16. 

1. A CORRSOION INHIBITING COMPOSITION FOR FINE MACHINERY COMPRISING A MAJOR PROPORTION OF A DIALKYL ESTER OF DIBASIC ALIPHATIC CARBOXYLIC ACID AS A LUBRICATING OIL, ABOUT 1% BY WEIGHT OF OIL-SOLUBLE PETROLEUM SULFONATE, ABOUT 1% OF DEGRASS, ABOUT 1% OF PENTAERYTHRITOL MONOOLEATE, ABOUT 0.5 TO 0.6% OF LECTHIN AND ABOUT 0.5% OF 2,6-DITERIARY BUTYL PARACESOL. 